Roof Parapet

As per the Reference Guide, appurtenances are exempt from this calculation, along with mechanical equipment and PV panels. I typically think of parapets as appurtenances, because by definition they are a less significant element associated with the roof. It sounds like that might not be the case for your parapet, however, which leaves this as more of a judgment call.

Do you generally include walking pads on roofs or lump that into the excluded category as well? Thanks

It's my understanding that walking pads are included. There are several walking pad products that meet the SRI requirements, although you can also require a conventional pad with an added coating. This can be pretty important, as walking pads can potentially make up a significant percentage of roof area.

The horizontal surface of the parapet can contribute to heat island. This surface is not an appurtenance (which would include things like ladders, pipes, antennae, etc.). Intent of the credit should be considered here so you don't get bogged down in meaningless analysis of course. Usually (big roof and typical parapet), the area of the top of a parapet would not change the outcome of the calculation for this credit, but you would want to look at it if significant. Imagine an 18-24" wide dark painted metal coping around a 2500 sf roof - around 10% of the roof area net of equipment. Might matter...and such buildings have been built. As well - parapet area can exceed walking pad area.